A "lost" landscape thought to have been painted by Pierre-AugusteRenoir will go on the auction block Sept. 29 on behalf of the Baltimore-born woman who purchased the artwork at a West Virginia flea market for $7.

"Paysage Bords de Seine," a 6-inch by 10-inch canvas dating from about 1879, is expected to fetch $75,000 to $100,000, according to Anne Norton Craner, the fine arts specialist for the Potomack Company, the Alexandria, Va., auction house overseeing the sale. She said that it's one of several depictions of the river Seine that the French Impressionist master created near the towns of Bougival and Chatou. The landscape was once linked to a Baltimore heiress.

The landscape is intentionally blurred and indistinct. Fast-moving swirls of green, purple and pink and a splash of white mimic the motion of the water and wind. The viewer glimpses the river through a scrim of shrubbery, while something gray and vertical looms on the far bank.

The Virginia-based buyer, who prefers to remain anonymous, purchased a box of odds and ends at a flea market just across the West Virginia state line and near her home in the Shenandoah Valley in late 2010 or early 2011. She didn't much care for the painting and said she would never have bid on it if the other stuff in the box hadn't caught her eye.

"There was a plastic cow that grabbed me, and a Paul Bunyan doll," said the woman, who lived in Baltimore until she was 4 years old. "And, I liked the frame. It was gold and ornate. I thought I could use it for something else if I cut out the painting."

But, for the next 18 months to two years, the painting rattled around the trunk of the Virginia woman's car and was stored in a shed with a busted window.

"Anne Craner flipped out when I told her that I tore off the brown paper on the back and threw it in the trash," the woman said.

Luckily, the buyer couldn't figure out how to dismantle the old frame and took the painting to her mother for advice. She'll remember their conversation to her dying day:

"There was a tag on the painting that said, 'Renoir, 1841-1919.' My mom said, 'You might not want to be so anxious to pull this apart.'"

"I said, 'C'mon, Mom, this can't be real.'

"Lo and behold, she was right. I guess it pays to listen to your mother."

The woman phoned the Potomack Company at the end of July because she was familiar with the auction house through the PBS television program "Antiques Roadshow."

"At the end of July, we got a call from a lady saying, 'I think I have a Renoir. Is it OK if I bring it in?'" Craner recalled.

"When she walked in, the painting was in a white plastic bag, and I thought, 'Here we go again. I'm going to have to be nice to this woman.' But, you just never know. We really do try to take time and see everyone who comes in. Thank goodness we did."

Craner gingerly opened the bag, removed the painting and bent down for a closer look. And, that's when she started to get excited.

"The painting had Renoir's radiant light," she said.

"It had the right colors. He was using any kind of brush stroke he could use — the full brush, the side of the brush and the tip of the brush. When you see something authentic, it just feels right. But, you can't go with your gut. You have to check it out."

The label on the painting's back provided the title and indicated that the painting had been purchased in 1926 from the Gallerie Bernheim-Jeune in Paris, one of the pre-eminent Renoir dealers.

The buyer was Herbert L. May, who at the time was married to a cousin of prominent Baltimore art collectors Claribel and Etta Cone. May's wife, Saidie Adler May, also donated more than 1,000 items to the Baltimore Museum of Art.

Herbert May had a special interest in landscape painting, according to Susan Helen Adler, a local historian who last year published a biography of her great-great aunt.

"Saidie really educated both her husbands in terms of buying art," Adler said. "Buying art and giving to museums was her whole life. If Saidie knew that the Renoir had been found in a flea market, she would have been ecstatic. She loved going to the markets and to the little old dusty shops and bargaining with the dealers and the artists."

The Mays divorced in 1927, the year after purchasing the Renoir. Chances are that the artwork stayed with Herbert May, though no one knows for certain. What happened to the painting in the intervening 85 years, and how it arrived at the West Virginia flea market, is a mystery.

But Elizabeth Haynie Wainstein, the owner of the Potomack Company, said that she is "95 percent certain" that the landscape that she will put up for auction is authentic.

"You can never say 100 percent for sure," she says. "There's always a possibility that previous authorities made a mistake."

For Wainstein, the crucial confirmation came when Craner found a listing for the work in Renoir's catalogue raisonne, or comprehensive catalog of the artist's known works. The listing was accompanied by an 86-year-old black-and-white photograph.

Because the catalog was published in 1880, while the artist was very much alive and available for consultation, Wainstein said, it's unlikely that "Paysage Bords de Seine" was painted by a follower of Renoir's rather than the master himself.

And, because the photograph matched the painting in Craner's hands down to the smallest detail — including a mark left by a historical accident — she strongly doubts that it's a forgery.

"There's even the exact same spot in the right-hand corner that looks like old fly dirt," she said.

"It isn't part of the painting itself. It was there in 1926 in this black-and-white photograph, and it's there on the painting now. That sealed the deal for me."

In addition, Craner said, because of the idiosyncratic color palette and the myriad brush strokes going every which way, this particular painting would be "a forger's nightmare."

"If I were going to forge a painting," she said, "I'd choose something simpler to copy."

Authenticating a work of art inevitably is fraught with peril. However, experts contacted by The Baltimore Sun said the Potomack Company used standard verification procedures.

For her part, the woman who found the Renoir is reeling a bit from her good luck — not to mention the media attention. In the past few days, she's been interviewed twice by the BBC. Radio stations in Finland, France and Germany are calling, and a request has just come in from Australia.

She's barely had time to think about how to spend her potential windfall, though her house could use new siding. But, she figures that someone close to her would love to see with her own eyes the river that Renoir painted.

"The first thing I'm going to do," she said, "is take my wonderful mother to France."

Images of "Poetry and Art in Rural Maryland," a project by artist Bill Dunlap and the University of Maryland Art Gallery to bring at least one mural to a barn in every Maryland county. • Read the story: Barnstorming artist takes murals to every Md. county